For decades, radiation shielding has been almost synonymous with bulky materials, such as concrete and/or lead, depending on the application. Concrete, often formulated with Boron, is effective as an attenuator of neutron radiation. In many neutron generating applications, including isotope generation for nuclear medical uses, several feet of borated concrete is required to attenuate neutron radiation to safe levels. Lead, although toxic, is an effective attenuator of high energy photonic radiation, such as X-rays and γ-rays.
Because of the bulk of concrete and lead as well as the mass of those materials necessary for effective shielding, most radiation-generating activities currently take place at facilities having substantial physical space and structure. Certain trends within nuclear science, for example, Positron Emission Tomography (PET), are leading towards the need to locate wide-spectrum radiation producing sources in facilities not originally designed to accommodate the weight and space requirements of conventional shielding. For example, radioisotopes used for PET often have a relatively short half-life necessitating that they be produced close to a patient. Also, the accelerator production of radioisotopes typically used for PET generates wide spectrum radiation including both photonic radiation and neutron radiation. Accordingly, there is a desire and need to practice wide-spectrum nuclear techniques in small-scale facilities where it is often not cost-effective and/or practical to create the physical structure necessary to support concrete and/or lead shielding.
Accordingly, there is a need for radiation shielding that is compact and light relative to conventional concrete or lead shielding. There is also a need for improved radiation shielding that shields wide spectrum radiation including photonic radiation and neutron radiation.